The role of differential distribution of intermediates between mitochondria, cytosol and endoplasmic reticulum in the circulation of steroid intermediates during steroid metabolism will be studied. The localization and organization of membrane-bound enzymes of steroid biosynthesis will be examined and the character of the molecules involved in the transfer processes will be investigated. We wish to see how far these functional systems are disturbed during tumorigenesis in testicular interstitial cells and adrenals and after the frank development of tumors.